1. Field of the Invention
The present invention relates to water treatment and recycling apparatus and, more particularly, to apparatus for recycling concentrate water from a reverse osmosis water purification unit.
2. Background of the Invention
Reverse osmosis (R/O) units have been used for years to obtain near pure water for human consumption and other uses. These units are often located on the premises of businesses and residences to serve potable water needs. The operation of an R/O unit is well known. Generally, one or more filters are located upstream to remove particulate matter of a size corresponding to five microns or more. The filtered water may be passed through an activated carbon filter to reduce the presence of chlorine, THM's, TCE, pesticides and other harmful and foul tasting chemicals.
The filtered water is introduced to one side of a semipermeable membrane under pressure. The water flowing through the membrane is effectively filtered by restricting passage of particles therethrough of a size down to 1/10,000 of a micron. This filtration will remove 99.99% of bacteria, viruses, cysts and pyrogens. Up to approximately 98% of various metals and chemicals commonly found in city water, as well as in water from natural springs, are removed. The filtered water is referred to as the permeate and the water containing the filtered elements is referred to as the concentrate. Representative R/O units are available from Kelco Water Engineering, Inc. of Tempe, Ariz. and include model numbers RO-TFC-MS, RO-TFC-MX3, RO-TFC-LPP, RO-CTA-MS, and RO-CTA-LPP.
During filtration, the water on the upstream side of the membrane, including particulate matter removed from the water passing through the membrane, is discharged. Thus, this water has a higher concentration of particulate and other matter than the water entering the R/O unit. In practice, two to three times as much water is discharged from the upstream side of the filter as is filtered. Because the filter has a very low porosity in order to effectively serve its filtering function, the production of 15 gallons per day at conventional city water pressure is the norm. This translates into approximately 45 gallons of water per day that is discarded into the drain or sewage system. Periodically, the upstream side of the manifold adjacent the membrane may be flushed to remove the filtered particles, etc. The flush water is generally conveyed to a drain and becomes part of the waste water of the business, residence or other place of use.
The ever present need and desire for essentially pure water for potable purposes must be balanced with the quantity of waste water produced by conventional R/O units. Where water is at a premium in terms of availability, a user may have to forego water treated by an R/O unit in favor of water conservation.